Note: Descriptions are shown in the official language in which they were submitted.
11~73~35
~ack round of the Invcntion
This invention relates to drainage devices and more
par~icularly to underwater drainage devices of the type dis-
closed in U.S. Patents 3,363,626 and 3,363,627. More spe-
cifically, the invention relates to the prevention of
noise in such underwater drainage devices as disclosed in
the aforementioned patents when used with suction where-
in prior art devices substantial noise is produced by
the device during operation by reason of air bubbling
through the water in the manometer chamber. The present
invention provides muffling means for reducing the noise
produced by such bubbling to an acceptable level.
In our prior patent 3,782,497, there is disclosed
a sound muffling device including a member which is in-
serted in the opening to atmosphere from the manometer
chamber. This member is provided with a tortuous passage-
way extending therethrough and such device to a certain
extent muffles the sound emanating from the device by
reason of the bubbling of gas through the water in the
manometer chamber. ~owever, the sound muffling device
disclosed in patent 3,782,497 is not entirely satisfac-
tory in reducing the sound from underwater drainage de-
vices to a level which is acceptable to patients. Accord-
ingly, it became necessary to improve upon such device.
Summar of the Invention
Y
The present invention provides an apertured baffle
plate in the large arm of the manometer chamber. This
baffle plate extends across the entire cross section of
the large arm of the water seal chamber adjacent the
lower end thereof and is provided with a plurality of
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fine holes therein. This apertured baffle plate serves to
break up the air which is passing into the large arm of the
manometer chamber from the opening to atmosphere in the small
arm of the manometer into a large number of small bubble streams
so that there are no large air bubbles formed in the water in
the large arm of the manometer chamber.
The invention is particularly directed toward a
drainage deviGe for draining fluids through a thoracotomy tube
from a pleural cavity. The drainage device has a collection
chamber having an inlet opening to be placed in fluid communi-
cation with a cavity to be drained, and a seal chamber having
first and second columns in communication with each other at
the lower ends thereof and adapted to receive a body of liquid
in the lower portion of the first and second seal chamber
columns. The upper end of the first seal chamber column is
in fluid communication with the collection chamber, and the
upper end of the second seal chamber column is in fluid com-
munication with a vacuum source. The device has a manometer
chamber comprising first and second columns in fluid communi-
cation with each other at the lower ends thereof and adaptedto receive a body of liquid in the lower portion of the first
and second manometer chamber columns. The upper portion of
the first manometer chamber column is in fluid c~nication with the
vacuum source and the upper portion of the second manometer
chamber is open to atmosphere. The improvement includes means
comprising a thin apertured baffle plate extending horizontally
across the lower end portion of the first manometer chamber
column. During operation of the drainage device, the baffle
plate forms an air plenum beneath the plate and prevents the
formation of large noise producing bubbles in the water above
the plate. The apertured baffle plate has at least 0.15 aper-
tures therein of approximately lmm in diameter per mm2 of plate
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surface area.
It has been found that the high noise level which
has been produced in underwater drainage devices of the type
shown in the aforementioned patents is caused by the formation
of large air bubbles in the water in the large arm of the mano-
meter chamber and in the breaking up of these large bubbles at
the surface of the water in the large arm of the manometer
chamber. Thus, by providing a means which prevents the for-
mation of the large air bubbles, this noise problem has been
obviated.
Prior patents 3,559,647; 3,683,913 and 3,782,497 all
disclose underwater drainage devices with air flow meters dis-
posed therein. Such air flow meters comprise a number of holes
formed in a plate in the large arm of the manometer chamber and
in the large arm of the water seal chamber. Such a series of
apertures provide a means for determining the quantity of air
passing through the manometer chamber and through the water seal
chamber. However, these devices do not perform the same function
as the presently disclosed sound muffling baffle plate inasmuch
as the apertures in these prior art devices are not sufficiently
small to prevent the formation of large air bubbles.
An object of the present invention is to provide a
sound muffling system for an underwater drainage device which
reduces the noise caused by air bubbling through
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the water in the manometcr cham~er to an ~ccepta~le levcl.
Another object of ~he prcsent invcntion is to ~ro-
vide in an underwater drainage device a plate having a
plurality of fine holes therein in the lower end of the
large arm of the manometer chamber which performs the
function of breaking up the large air bubbles normally
formed in the water in the manometer chamber into streams
of small bubbles so as to reduce the noise produced by
the drainage device during operation.
Other objects and many of the attendant advantages
of the present invention will become more readily ap-
parent upon consideration of the following detailed
specification.
Detailed Description of the Invention
There follows a detailed description of a preferred
embodiment of the invention, together with accompanying
drawings. However, it is to be understood that the de-
tailed description and accompanying drawings are pro-
vided solely for the purpose of illustrating a preferred
embodiment and that the invention is capable of numerous
modifications and variations apparent to those skilled
in the art without departing from the spirit and scope
of the invention.
Figure 1 is a sectional view through the center
plane of an underwater drainage apparatus according to
the present invention; and
Figure 2 is a plan view of the sound muffling de-
vice according to the present invention.
Referring now more specifically to the drawings,
there is shown at 10 an underwater drainage device of the
general type disclosed in prior U.S. patent 3,363,626 and
r 3,363,627. Such an underwater drainage device includes
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three chambers, a collection chamber 11, ~enerally U-shapcd
underwater seal chamber 12 and a gener~lly U-sha~cd ~rcs-
sure manometer chamber 13. The collection chamber 11 is
provided with an opening 14 which is adapted to be con-
nected to a thoracotomy tube connected to the patient.
Liquid from the patient's pleural cavity flows through the
thoracotomy tube and is collected in the collection chamber
11 while gases are drawn through the underwater seal cham-
ber 12 and pass out through a connection 15 to a vacuum
source.
The manometer chamber 13 comprises a small arm 16
which has the upper end thereof connected to atmosphere
and a large arm 17 which has the upper end thereof in
communication with the vacuum source 15 and the large
arm of the underwater seal chamber 12. The manometer
chamber serves to regulate the degree of vacuum maintained
within the device by the amount of water in the large arm
17 of the manometer chamber. During operation of the de-
vice air passes downwardly through the small arm 16 of the
manometer chamber and bubbles through the water in the large
arm 17 of the manometer chamber and out through the con-
nection with vacuum source 15.
The production of large air bubbles passing through
the water in the large arm of the manometer chamber and the
breaking up of these bubbles as they reach the surface of
the water in the chamber causes considerable noise and
this has been a source of annoyance to patients. According
to the present invention there is provided a perforated
plate 18 which extends across the lower end of the large
arm of the manometer chamber. As can be seen in the drawing
this plate 18 serves to break up the air passing downwardly
through the small arm of the manometer chamber into a
series of streams of fine bubbles and the breaking of these
fine bubbles on the surface of the water in the large arm
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of the manometer chamber do not create nearly so great a noise
level and thus, disturbances of the patients by the noise of
operation of the underwater drainage device is considerably
reduced.
The perforated plate 18 is shown in greater detail in
Figure 2 and it can be seen that in the particular embodiment
shown the plate is provided with approximately 150 holes of
a diameter of lmm with the plate being essentially square and
26mm in length, or approximately 0.22 apertures therein of
approximately lmm in diameter per mm of plate surface area.
It is preferred that the plate 18 has at least 100 apertures
therein, the apertures being approximately lmm in diameter, or
at least 0.15 apertures therein of approximately lmm in diameter
per mm2 of plate surEace area.
It can be seen that during operation an air plenum is
formed beneath the plate 18 and a combination of the air plenum
beneath the perforated plate with the fine small holes in the
plate prevent the formation of the large air bubbles which have
been responsible for the production of objectionable noise
levels in prior art devices. The perforated plate extends
across the entire cross section of the large arm of the mano-
meter chamber and forms the function of muffling the sounds
emanating from the underwater drainage device to such an extent
that the rest of patients using the device is not disturbed.
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